8176026: SA: Huge heap sizes cause a negative value to be displayed in the jhisto heap total

Reviewed-by: cjplummer, kevinw, ysuenaga

Author: jyukutyo

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHistogram.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -65,8 +65,8 @@ public void printOn(PrintStream tty) {
     ObjectHistogramElement.titleOn(tty);
     Iterator<ObjectHistogramElement> iterator = list.listIterator();
     int num=0;
-    int totalCount=0;
-    int totalSize=0;
+    long totalCount=0;
+    long totalSize=0;
     while (iterator.hasNext()) {
       ObjectHistogramElement el = iterator.next();
       num++;

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHistogramElement.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -47,7 +47,7 @@ public void updateWith(Oop obj) {
   }
 
   public int compare(ObjectHistogramElement other) {
-    return (int) (other.size - size);
+    return Long.compare(other.size, size);
   }
 
   /** Klass for this ObjectHistogramElement */